1. Field of the Invention
The present disclosure relates to a liquid treatment apparatus and a liquid treatment method used to conduct liquid treatment such as cleaning and etching for substrates by supplying a treatment liquid to a lower surface of the substrate while spinning it.
2. Description of Related Art
There have been known conventional substrate cleaning apparatuses that clean substrates such as semiconductor wafers (hereinafter, also referred to simply as “wafer(s)”) by supplying a cleaning liquid to a substrate which is rotating and held in horizontal posture.
JP9-290197A describes a substrate processing apparatus that includes a spin chuck for retaining a wafer in horizontal posture and rotating the wafer; and a cleaning liquid supply pipe extending inside a rotating shaft of the spin chuck and having an opening for ejecting cleaning liquid towards the center of the lower surface of the wafer retained by the spin chuck. The peripheral area of the wafer lower surface may not be sufficiently cleaned if the cleaning liquid is ejected towards the center of the lower surface of the wafer W.
JP2005-353739A describes a substrate processing apparatus that includes a spin chuck for retaining the wafer in horizontal posture and rotating the wafer; and a two-fluid nozzle for jetting a two-fluid spray towards the upper surface of the wafer retained by the spin chuck. The two-fluid spray is formed from a nitrogen gas and a treatment liquid such as a chemical liquid and is jetted in a band-like form having a length nearly equivalent to the radius of the wafer. JP2005-353739A suggests that such a two-fluid nozzle may also be disposed below the lower surface of the wafer to clean the lower surface. However, a specific configuration of such an arrangement is not disclosed. In addition, it is described in JP2005-353739A that the two-fluid nozzle ejects only a two-fluid spray of a mixture of liquid and gas.
JP2008-130763A describes a substrate processing apparatus that includes a spin chuck for retaining the wafer in horizontal posture and rotating the wafer; a two-fluid nozzle for jetting a two fluid spray towards the upper surface of the wafer retained by the spin chuck, the two fluid spray being a mixture or a nitrogen gas and a treatment liquid such as a chemical liquid and is jetted in a band-like form having a length nearly equivalent to a diameter of the wafer; and another nozzle for ejecting a treatment fluid such as deionized water (DIW) towards the central portion of the upper surface of the wafer W. In the apparatus of JP2008-130763A, when a two-fluid nozzle jets a two fluid-spray onto the upper surface of a wafer W, the two-fluid nozzle scans the upper surface of the wafer W which is not rotating. Cleaning of the lower surface of the wafer W is not described in JP2008-130763A.